Run clang-format on the entire repo

This patch clang-formats the entire repo. Third-party code is
excluded.

I needed to fix up the .clang-format file so that all the header
includes are ordered properly. I could have sworn that it used to work
without the extra modification, but I guess not.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: I64bb9f2c795401393f9dfe2fefc4f04cb36b52f6
diff --git a/build_tests/gflags.cc b/build_tests/gflags.cc
index 20ce987..b2f0d08 100644
--- a/build_tests/gflags.cc
+++ b/build_tests/gflags.cc
@@ -2,6 +2,4 @@
 
 DEFINE_int32(test_flag, 0, "Test command-line flag");
 
-int main() {
-  return FLAGS_test_flag;
-}
+int main() { return FLAGS_test_flag; }